From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E5DF337F8C2 for ; Wed, 8 Apr 2026 18:08:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775671737; cv=none; b=hRtKndWNdLxSTZon4yquL70wOqp6g7ZLYCK9QrNoJ/JjCjk0o+yZMs4VVa5Y/LPmT0EYF348cY+ChZulKku+DOsESLHqj4hGpv8JY85v9fEkLIg8SsbJG2poaIdE8tLrFZTBKgwA4p7NS8d95Eo6Z+MB1tdsc31fLwaDboikdm0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775671737; c=relaxed/simple; bh=gjoZ6EXEho/9YKSh2vZc0t46JYCGruU35fBS6/DCjSA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=QSqxXzGc6IiuBebGUymPFx5P2N50QIsUL2yqhiEen0lmcqhFRmYteCSxGOcY9Res8mrattoVjxJFFUBvU0vJuMWppPhMMrKwxGAeXbB1Zi7kII4wXb7d+5HjFAtBPJKGEnRtHh9Gs14mYYMnBSiQSr0wEu2TYQBjCuS0jIeDkuY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=rleA7Q5F; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="rleA7Q5F" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9C95EC19421; Wed, 8 Apr 2026 18:08:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1775671736; bh=gjoZ6EXEho/9YKSh2vZc0t46JYCGruU35fBS6/DCjSA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=rleA7Q5F12Eow+XD+tZnHSctqeL3D9Ff1H88myZ+EhzFCsEUxCY1TeHKrN5vUd1on lSidBKoUoe4z4cE6FYjOLQmDIw47e7Uwlf/RIUdizj0rh+vJA1an0TWKtaLPnWW11+ SYU2UcATvkP8dItxb9ScLadbutkefcyaAVQhk+s93WT2rjqJOk2LyR1FxHXHuwRt8s G66+rqKRLf6H32b5HiQ72uCtPNZyyVuwsAvYzjdDhgQFiLub2wBnweSp0v9TX8w9sa mtVXpahw9aqEGyFqC2Rw32mb70iI0hqLV9Ew9maNMOjASYCmDvYEg8reM/oERKDUjs 97dsgB9d8q0RQ== Date: Wed, 8 Apr 2026 18:08:55 +0000 From: Jaegeuk Kim To: "David Hildenbrand (Arm)" Cc: Christoph Hellwig , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] f2fs: do not support mmap write for large folio Message-ID: References: <20260406154940.2407853-1-jaegeuk@kernel.org> <2aee26dd-703b-47c4-9210-f70ffa6faf09@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2aee26dd-703b-47c4-9210-f70ffa6faf09@kernel.org> On 04/08, David Hildenbrand (Arm) wrote: > On 4/8/26 07:03, Christoph Hellwig wrote: > > On Tue, Apr 07, 2026 at 10:58:11PM +0000, Jaegeuk Kim wrote: > >> On 04/06, Christoph Hellwig wrote: > >>> > >>> Why? And how is this not breaking applications? > >> > >> Since we only support the large folio on the read case. > > > > In general spelling such basic out in the commit log, and even comments > > is really helpful. I'm curious how this works, though - by the time > > you read a large folio you don't know if it will ever be written to. > > Why are only large folios supported for read? > > Where is that allocation logic and how can that path even be triggered? > > Also, usually we check for large folios by testing the actual folio, not > whether the mapping supports them? https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v7.0-rc7&id=05e65c14ea59a401cec4284e9d612f9d5dc1b3f8 Currently I think it's simple to check the mapping in our case. > > -- > Cheers, > > David